[K12OSN] Switch Issues

[Jim McQuillan]

On Thu, July 27, 2006 3:32 pm, Eliot, Dan wrote:
> Here's the deal...
>
> The technology folks in my district are less than excited that I want to
> set up a LTSP Linux Lab.  We are currently a Window only shop, and the
> already stretched Tech staff is not interested in adding another OS they
> would be responsible for (fair enough).
>
> They are particularly NOT excited to set it up so that the switch in my
> building allows another IP range.  Currently, our building allows
> 10.11.150.xxx IP addresses.  I would like them to add another IP range so
> that the DHCP servers ("regular" and LTSP) don't conflict.  So ideally,
> they would add 10.11.155.xxx as the IP range for LTSP clients.
>
> OK, a couple of questions for the experts on this list?
>
> (1)  Is there any way to allow two DHCP servers to "coexist" in the same
> IP range WITHOUT regular clients getting IPs from the LSTP server?  In
> other words, can I just stick with 10.11.150.xxx and not have the two
> machine groups mess with each other.



The problem is NOT that the two dhcp servers exist in the same IP address
range.

The problem is when the two dhcp servers are on the same PHYSICAL network.

A DHCP request is sent out as an Ethernet broadcast.  There is NO ip
address involved at this point.  If you have 2 dhcp servers on the same
physical lan, then which DHCP server answers first will be the one that
the client listens to.

Some possiblities exist, such as:

  1) Run your ltsp dhcpd server on a port other than 67/68.  Such as
     port 1067/1068.  There's information about doing that on the
     LTSP wiki.  The problem is, you can't use PXE to boot.  You MUST
     use Etherboot.

  2) Run separate physical lans, so that the LTSP workstations aren't
     on the same network as the windows boxes.  A managed switch will
     allow you to setup vlans, so that it can appear as separate
     networks.

  3) Use the Windows DHCP server to serve all of your DHCP needs.
     You'll need to add root-path and next-server entries to your
     windows dhcp config.

  4) Use the Linux DHCP server to serve all of your DHCP needs.
     This way, you could get rid of the windows dhcp server.


Hope that helps,

Jim McQuillan
jam at Ltsp.org



>
> (2)  On a related note, the machines that I will be "LTSPing" currently
> have Win95.  I will be using floppy disks to bootstrap to the LTSP server.
>  Ideally, it'd be nice for the machines to go to the normal Windows DHCP
> server when they are running Windows 95, but go to the LTSP DHCP server
> when I start a LTSP floppy boot.  Any suggestions for making this work
> seamlessly (or with as few seams as possible)?
>
> Thanks in advance for any input.
> Dan
>
>
> ----
> Dan Eliot, Computer Science Teacher
> El Dorado High School
> 1651 N. Valencia, Placentia, CA, USA
> deliot at pylusd.org, 714-993-5350 x7506
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